Ferrous Gluconate Oral Solution

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Ferrous Gluconate Oral Solution contains NLT 94.0% and NMT 106.0% of the labeled amount of ferrous gluconate dihydrate (C₁₂H₂₂FeO₁₄ · 2H₂O).

2 IDENTIFICATION

2.1 A. Thin-Layer Chromatography

Standard solution: 10 mg/mL of USP Potassium Gluconate RS in water

Sample solution: A filtered solution in water, equivalent to 10 mg/mL of ferrous gluconate dihydrate from Oral Solution

2.1.1 Chromatographic system

(See Chromatography 〈621〉, Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic silica gel

Application volume: 5 µL

Developing solvent system: Alcohol, ethyl acetate, ammonium hydroxide, and water (50:10:10:30)

Spray reagent: Dissolve 2.5 g of ammonium molybdate in 50 mL of 2 N sulfuric acid in a 100-mL volumetric ask. Add 1.0 g of ceric sulfate, swirl to dissolve, and dilute with 2 N sulfuric acid to volume.

2.1.2 Analysis

Samples: Standard solution and Sample solution

Develop the chromatogram until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, and dry at 110° for 20 min. Allow to cool, and spray with Spray reagent. Heat the plate at 110° for about 10 min. Acceptance criteria: The principal spot of the Sample solution corresponds in color, size, and R value to that of the Standard solution. F

2.2 B. Ferrous Ion

Sample solution: Equivalent to 5 mg/mL of ferrous gluconate dihydrate from a dilution in water of the Sample solution obtained in Identification test A

Analysis: Add potassium ferricyanide TS to the Sample solution.

Acceptance criteria: The solution yields a dark blue precipitate.

3 ASSAY

Procedure

Sample: An accurately measured volume of Oral Solution, equivalent to 1.2 g of ferrous gluconate dihydrate Blank: Proceed as directed in the Analysis without the Sample.

Titrimetric system

(See Titrimetry 〈541〉.)

Mode: Direct titration

Titrant: 0.1 N ceric sulfate VS

Indicator: Orthophenanthroline TS

Endpoint detection: Visual

Analysis: Dissolve the Sample in a cooled mixture of 80 mL of recently boiled water and 80 mL of 2 N sulfuric acid. Add orthophenanthroline TS, and immediately titrate with Titrant until a change in color. Perform a Blank determination.

Calculate the percentage of the labeled amount of ferrous gluconate dihydrate (C₁₂H₂₂FeO₁₄ · 2H₂O) in the portion of Oral Solution taken:

Result = {[(V_S − V_B ) × N × F]/W} × 100

V_S = Titrant volume consumed by the Sample (mL)

V_B = Titrant volume consumed by the Blank (mL)

N = actual normality of the Titrant (mEq/mL)

F = equivalency factor, 482.2 mg/mEq

W = nominal amount of ferrous gluconate dihydrate in the Sample taken (mg)

Acceptance criteria: 94.0%–106.0%

4 OTHER COMPONENTS

Alcohol Determination 〈611〉: 6.3%–7.7% of C₂H₅OH

5 SPECIFIC TESTS

pH 〈791〉: 3.4–3.8

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers.

Labeling: Label the Oral Solution in terms of the content of ferrous gluconate dihydrate (C₁₂H₂₂FeO₁₄ · 2H₂O) and in terms of the content of elemental iron.

USP Reference Standards 〈11〉

USP Potassium Gluconate RS.